sci.electronics.repair - 25 new messages in 9 topics - digest

sci.electronics.repair
http://groups.google.com/group/sci.electronics.repair?hl=en

sci.electronics.repair@googlegroups.com

Today's topics:

==============================================================================
TOPIC: Dead Sony KV-T25SZ8 TV
http://groups.google.com/group/sci.electronics.repair/t/a211bd1fd48660f2?hl=en
==============================================================================

== 1 of 8 ==
Date: Sun, Mar 13 2011 11:44 pm
From: "Phil Allison"

"Clifford Heath"
>
> However, HOTs are very strange devices. If you just do the basic
> two-diode test, you'll probably consider that a good one has failed.
> That's what I did :)... something to keep in mind.
>

** You need a " Power Transistor Tester" - published as a full construction
article in EA magazine back in May of 1988 by me. Altronics and Jaycar had
kits for it at one time.

It will reasonably accurately test the beta (or Hfe) of any power transistor
OR power Darlington pair OR horizontal deflection transistor. Very cheap
to make - uses only a few passives, a couple of red LEDs and a WW pot.

No PCB was used as it take only minutes to wire up the bits once they are
all fitted into a small jiffy box.

It will also allow close matching ( ie Vbe match) of groups of power
transistors that must operate in parallel.

Requires an external 12 volt DC source.

I would post the schem on ABSE, but like so many others I no longer have
access to the site.

..... Phil

== 2 of 8 ==
Date: Mon, Mar 14 2011 1:26 am
From: "Wild_Bill"

It's been a long time since I dealt with CRT horiz output
sections/transistors, and the latter ones were in VGA monitors.

In the Repair FAQ there are safety, testing and troubleshooting procedures
for horiz section faults, including the lightbulb in series with the HOT B+
setup, IIRC.

The HOTs (transistors) are fairly rugged semis, but operating at 15+kHZ and
high peak/fast risetime conduction cycles.

FWIW section..

A few conditions wrt HOT failures that I can recall at the moment include
bad/cold/broken solder connections, loss of horiz drive and drifting
values/faults in the tuning capacitors (the small value 1 and 2kV caps).

Small low voltage/battery powered testers aren't very reliable, IMO, for
testing/evaluating HOTs, since reliable leakage testing at higher voltages
than most small testers are capable of, should be performed to determine the
junction's performance compared to the datasheet published specs.

The above point being that one rarely knows for sure if they're receiving
genuine exact replacement parts nowadays, and testing before installation is
likely the best way to find out if the part are bogus.

My recommendations (and many other archived repair recommendations) for Sony
TVs and monitors, is to research the failure and buy all the recommended
repair parts from a Sony authorized distributor, especially for PSU and H,V
sweep faults.

--
Cheers,
WB
.............

"Sylvia Else" <sylvia@not.here.invalid> wrote in message
news:8u5dluFctkU1@mid.individual.net...
> On 13/03/2011 4:29 PM, Sylvia Else wrote:
>
> I've bitten the bullet, and bought a new television.
>
> Still, I'm puzzled by the failure in the old one. The transistor has
> clearly failed, as far as I can see. Removing the small inductor mentioned
> above stops the clicking noise, which is consistent with there no longer
> being a short across the SMPS.
>
> I'd have expected the set to now turn on and produce sound. But it
> doesn't.
>
> The SMPS uses a quasi-resonant circuit, and disconnecting the inductor has
> a side effect of removing the feedback for the SMPS. But on my, admittedly
> limited, understanding of such circuits, it should still work.
>
> Sylvia.

== 3 of 8 ==
Date: Mon, Mar 14 2011 1:51 am
From: "Phil Allison"

"Wild_Bull"
>
> FWIW section..
>
> A few conditions wrt HOT failures that I can recall at the moment include
> bad/cold/broken solder connections, loss of horiz drive and drifting
> values/faults in the tuning capacitors (the small value 1 and 2kV caps).
>

** Not to forget arcing inside the CRT or the horizontal transformer.

> Small low voltage/battery powered testers aren't very reliable, IMO, for
> testing/evaluating HOTs,

** 99 % of them cannot do any test on them at all.

> since reliable leakage testing at higher voltages than most small testers
> are capable of, should be performed to determine the junction's
> performance compared to the datasheet published specs.

** Pure gobbledegook.

> The above point being that one rarely knows for sure if they're receiving
> genuine exact replacement parts nowadays,

** Instead of what - fakes ??

> and testing before installation is likely the best way to find out if the
> part are bogus.

** Absolute bullshit.

No simple test will reveal a device that is merely sub-standard or of a
similar but cheaper type to the original.

The only way is to deal with reliable suppliers ONLY.

> My recommendations (and many other archived repair recommendations) for
> Sony TVs and monitors, is to research the failure and buy all the
> recommended repair parts from a Sony authorized distributor, especially
> for PSU and H,V sweep faults.

** Wear a belt and braces too - do you ??

.... Phil

== 4 of 8 ==
Date: Mon, Mar 14 2011 4:06 am
From: Sylvia Else

On 14/03/2011 7:51 PM, Phil Allison wrote:
> "Wild_Bull"
>>
>> FWIW section..
>>
>> A few conditions wrt HOT failures that I can recall at the moment include
>> bad/cold/broken solder connections, loss of horiz drive and drifting
>> values/faults in the tuning capacitors (the small value 1 and 2kV caps).
>>
>
> ** Not to forget arcing inside the CRT

In a vacuum?

or the horizontal transformer.

Sylvia.

== 5 of 8 ==
Date: Mon, Mar 14 2011 4:16 am
From: "Phil Allison"

"Stupider than Anyone Else.
>
>>
>> ** Not to forget arcing inside the CRT
>
> In a vacuum?
>

http://en.wikipedia.org/wiki/Vacuum_arc

** One of the most common causes of HOT failures.

Dumbass.

.... Phil

== 6 of 8 ==
Date: Mon, Mar 14 2011 8:25 am
From: "Wild_Bill"

Arcing, shorts and HV leakage can all take place within a CRT.
I've seen several CRTs that had HV leakage to the Focus element (didn't
damage the HOT though).. there may be some examples in the Repair FAQ of
this type of fault and other CRT faults.

--
Cheers,
WB
.............

"Sylvia Else" <sylvia@not.here.invalid> wrote in message
news:8u6b4pFhe5U1@mid.individual.net...

> In a vacuum?
>
> or the horizontal transformer.
>
> Sylvia.

== 7 of 8 ==
Date: Mon, Mar 14 2011 3:43 pm
From: Clifford Heath

On 03/14/11 17:44, Phil Allison wrote:
> ** You need a " Power Transistor Tester" - published as a full construction

Thanks.

> I would post the schem on ABSE, but like so many others I no longer have
> access to the site.

You mean you have no access to ABSE? Spend $US3.95 at www.teranews.com and
get free lifetime access to all the binary groups, limited to 50MB/day.

Clifford Heath.

== 8 of 8 ==
Date: Mon, Mar 14 2011 3:46 pm
From: Stroonz

On Mar 13, 1:11 am, "Phil Allison" <phi...@tpg.com.au> wrote:

>
> There is an inbuilt resistor from B to E in nearly all HOTs of 20 ohms or
> less.

******Bollocks.

Most horiz output internal resistors are between 25 and 50 ohms.
Besides, 20 ohms isn't 5.7ohms. In circuit, E to B reads an ohm or
under as the secondary of the horiz driver transformer is directly
across it.. Out of circuit, a reading of 5.7 ohms E to B is a bad
transistor. It's not common in horizontal outputs, but an E to B
short does happen.

On Mar 13, 1:11 am, "Phil Allison" <phi...@tpg.com.au> wrote:
> ** Probably normal.

**** More likely a stupid answer.

A common problem in Sonys is a bad solder connection on the secondary
of the horiz driver transformer, so instead of reading under an ohm,
the cold solder causes a reading of several ohms up to the internal
resistor value. Simply resoldering the horiz driver will restore
proper reading if the output is otherwise OK.

Twit.

Hey, this is fun!!!!!

==============================================================================
TOPIC: Boss TU-120 Electronic Tuner Schematic Roland LED Strobe Guitar Tuning
http://groups.google.com/group/sci.electronics.repair/t/9beb1a7b35ce5c6e?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Mar 14 2011 2:01 am
From: "Wild_Bill"

There is an 880Hz output, I think, as the chart in the back of the
Instructions booklet shows 880 as an A note with the selector switch in the
High Octave setting.

It's helpful that you brought this up, and although I'd looked at the chart
previously and noted the selections covering frequencies of 130.81 to
996.76, I hadn't made the connection.
This appears to be another example of RTFM.

If you've ever heard the radio comedy routine where people call in to ask
Mr. Obvious for advice, it's a funny version (although it's all scripted,
not real).
Mr. Obvious, I think I have a wild animal under my sink.. (questions,
replies).. oh, and there's a switch by my sink that doesn't seem to have any
purpose, doesn't turn on any lights, (more).

I'd considered connecting the older unit to the newer tuner, but I haven't
since I wasn't sure about the output from the Monitor jack of the older unit
being an overload for the input of the newer tuner.
When I saw the freq readings, I was convinced that the older unit needed
repaired.

--
Cheers,
WB
.............

<hrhofmann@att.net> wrote in message
news:6bf2e47c-9e4f-4d37-b0e5-dcfff334981d@o21g2000prn.googlegroups.com...

Does the questionable unit have an 880 setting? Can you cross-
reference the good unit to the questionable unit at any frequency?

==============================================================================
TOPIC: EARN DOLLARS ONLINE - FROM FOREX MARKET - 100% FREE
http://groups.google.com/group/sci.electronics.repair/t/c9777f80f166f1e7?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Mar 14 2011 3:57 am
From: surya maha

http://usaforextradingonline.blogspot.com

==============================================================================
TOPIC: CHATTING GIRLS - DATING TIPS -SEXY VIDEOS HERE
http://groups.google.com/group/sci.electronics.repair/t/19047b60646492ab?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Mar 14 2011 5:45 am
From: devi vithya

http://love4indianpeople.blogspot.com

==============================================================================
TOPIC: Marshall JCM 2000, 1998
http://groups.google.com/group/sci.electronics.repair/t/3338dc78a01d3b6d?hl=en
==============================================================================

== 1 of 4 ==
Date: Mon, Mar 14 2011 5:50 am
From: "N_Cook"

Marshall replacement £46 , same duff construction as this one?

== 2 of 4 ==
Date: Mon, Mar 14 2011 9:08 am
From: "Arfa Daily"

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:ill2ur$7hv$1@news.eternal-september.org...
> Marshall replacement �46 , same duff construction as this one?
>
>

I would expect it to probably be a ringer for what was already in there. If
the amp is really from 1998, then duff construction or not, it ain't done
bad, and if the new one does another 13 years, it's not going to come back
on you, is it ? And, if in the intervening 13 years since it was made,
Marshall have had a lot of them fail, then maybe they've taken this up with
Dagnell, and got them to improve the situation ? I would stop agonising over
it, and just stick the new one in, and write out the hundred quid bill for
the owner ...

Arfa

== 3 of 4 ==
Date: Mon, Mar 14 2011 3:32 pm
From: "Phil Allison"

"N_Cook"
>
> Marshall replacement £46 , same duff construction as this one?
>

** Of course.

Only way to fix the problem is to find someone willing to rewind the
original transformer with high temp enamel wire - ie 180C rate instead of
the 120C rated stuff used by Dagnall.

Or you could fit a small fan blowing on the tranny....

..... Phil

== 4 of 4 ==
Date: Mon, Mar 14 2011 4:05 pm
From: "Gareth Magennis"

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:8u7jc5Fd98U1@mid.individual.net...
>
> "N_Cook"
>>
>> Marshall replacement �46 , same duff construction as this one?
>>
>
> ** Of course.
>
> Only way to fix the problem is to find someone willing to rewind the
> original transformer with high temp enamel wire - ie 180C rate instead of
> the 120C rated stuff used by Dagnall.
>
> Or you could fit a small fan blowing on the tranny....
>
>
> ..... Phil
>

I'll go with Arfa's suggestion.
Pay the �46 and when it breaks in 13 years time, we can then re-assess the
situation.

Though the small fan idea is a good one IMHO. Might extend that period to
26 years or more.

Gareth.

==============================================================================
TOPIC: Plugs but no jacks
http://groups.google.com/group/sci.electronics.repair/t/387c4b30df150ab0?hl=en
==============================================================================

== 1 of 5 ==
Date: Mon, Mar 14 2011 6:56 am
From: Fuddy Dud

Everybody sells 3.5mm plugs but nobody sells 3.5mm jack that you can
mount and solder wires to. Is there a source? Most dealers don't even
know the difference.

--
All is as it is.

== 2 of 5 ==
Date: Mon, Mar 14 2011 7:24 am
From: "Geoffrey S. Mendelson"

Fuddy Dud wrote:
> Everybody sells 3.5mm plugs but nobody sells 3.5mm jack that you can
> mount and solder wires to. Is there a source? Most dealers don't even
> know the difference.

Search on "stereo headphone jack pcb" on eBay. You will find plenty of
people selling them "buy it now" (outright sale, not an auction).

In my experience the vendors from Hong Kong that include the postage
in the price sell decent quality and ship via registered mail.

Still it pays to look carefully at what is being sold, there are all kinds
of quality, mounting options, etc.

If you are in the US or UK, you might want to try Farnell. Farnell sells almost
everywhere in the world, but they have $35 mininum SHIPPING CHARGE in
some places. They sell many grades of quality, none are the out of spec
junk sold at DIY stores, flea markets, etc.

Note that shipping from EU countries (including the UK) is relatively cheap
and reliable. Shipping from the US to other countries is slow and unreliable.

Geoff.

--
Geoffrey S. Mendelson N3OWJ/4X1GM
Those who cannot remember the past are condemned to misquote it.

== 3 of 5 ==
Date: Mon, Mar 14 2011 8:10 am
From: Jeff Liebermann

On Mon, 14 Mar 2011 09:56:28 -0400, Fuddy Dud <nognoggin@yahoo.com>
wrote:

>Everybody sells 3.5mm plugs but nobody sells 3.5mm jack that you can
>mount and solder wires to. Is there a source? Most dealers don't even
>know the difference.

The magic Google buzz word is "3.5mm panel mount jack". For example:
<http://www.radioshack.com/product/index.jsp?productId=2062450>
You'll also need to specify 2, 3, or 4 (iPhone) conductors.

<http://www.schurter.ch/var/schurter/storage/ilcatalogue/files/document/datasheet/en/pdf/typ_4832.1200.pdf>
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 4 of 5 ==
Date: Mon, Mar 14 2011 8:14 am
From: "Wild_Bill"

It's likely that the naming of the jack is different when listed by
different suppliers. You don't say where you're located, or where you've
tried to find them.

In the U.S. that Shack store sells them.. I've bought both the 1/8" mini
(3.5mm) and the 3/32" submini (2.4?mm) sizes there in recent months.

The two styles of 1/8" size stereo phone jacks are p/n 274-0246 and 274-0249
(they might also have mono jacks).

The jacks can be described various ways..

Mini phone jack (not related to telephone)
Phone jack
Headphone/headset jack
Earphone jack
Audio jack, mini audio jack
1/8" mini jack
Mini TRS jack (stereo)

--
Cheers,
WB
.............

"Fuddy Dud" <nognoggin@yahoo.com> wrote in message
news:h8pfp.23379$hP6.1133@newsfe19.iad...
> Everybody sells 3.5mm plugs but nobody sells 3.5mm jack that you can mount
> and solder wires to. Is there a source? Most dealers don't even know the
> difference.

== 5 of 5 ==
Date: Mon, Mar 14 2011 9:48 am
From: Smitty Two

In article <h8pfp.23379$hP6.1133@newsfe19.iad>,
Fuddy Dud <nognoggin@yahoo.com> wrote:

> Everybody sells 3.5mm plugs but nobody sells 3.5mm jack that you can
> mount and solder wires to. Is there a source? Most dealers don't even
> know the difference.

I buy these by the 100 and use them frequently. Not really esoteric.
Even have a customer-designed product that I had to source a jack with a
small-pattern mounting nut to fit a machined pocket. It was about .010"
smaller across the flats than the ones I'd been buying.

Your use of "everybody" and "nobody" seem a tad hyperbolic.

==============================================================================
TOPIC: Noisy GE WPRE6100G1WT washing machine
http://groups.google.com/group/sci.electronics.repair/t/ec8ea060f834aa36?hl=en
==============================================================================

== 1 of 3 ==
Date: Mon, Mar 14 2011 10:00 am
From: Beloved Leader

This is not really an electronics problem, but members of this group
work on everything. If there's a more appropriate group, then I'll
gladly post the qustion over there.

We have a pretty new GE WPRE6100G1WT top load washing machine. We
purchased the machine in November 2008. It is used in a private
residence to run maybe 3 loads per week. The suspension rod assemblies
were replaced under warranty over a year ago.

New problem: seems to agitate much more quickly than expected. Also,
there are loud clanking signs at the end of each half of the agitation
motion. I mean, spin clockwise, CLANK, spin counterclockwise, CLANK.
Finally, for a few seconds on Saturday, a loud screeching came from
within during agitation. The screeching noise "went away by
itself." (I hate using that phrase, but it did.) There was no burning
smell.

If you overlook the noise, then you can go ahead and use the machine
to run a load of laundry. It completes a wash-spin-rinse-spin sequence
unevently, other than the noises. That screeching, the one time it
occurred, was quite disconcerting, though.

I'm thinking it's the transmission. We don't know if it is still under
warranty or not, and the GE call taker can't really advise on this. I
will see if I can find a GE technician later this afternoon.

Thanks.

== 2 of 3 ==
Date: Mon, Mar 14 2011 10:35 am
From: "N_Cook"

Beloved Leader <Kim_Jong_Il@volcanomail.com> wrote in message
news:e047b65f-247d-4a1d-a2cd-e3ce763aec4d@k15g2000prk.googlegroups.com...
> This is not really an electronics problem, but members of this group
> work on everything. If there's a more appropriate group, then I'll
> gladly post the qustion over there.
>
> We have a pretty new GE WPRE6100G1WT top load washing machine. We
> purchased the machine in November 2008. It is used in a private
> residence to run maybe 3 loads per week. The suspension rod assemblies
> were replaced under warranty over a year ago.
>
> New problem: seems to agitate much more quickly than expected. Also,
> there are loud clanking signs at the end of each half of the agitation
> motion. I mean, spin clockwise, CLANK, spin counterclockwise, CLANK.
> Finally, for a few seconds on Saturday, a loud screeching came from
> within during agitation. The screeching noise "went away by
> itself." (I hate using that phrase, but it did.) There was no burning
> smell.
>
> If you overlook the noise, then you can go ahead and use the machine
> to run a load of laundry. It completes a wash-spin-rinse-spin sequence
> unevently, other than the noises. That screeching, the one time it
> occurred, was quite disconcerting, though.
>
> I'm thinking it's the transmission. We don't know if it is still under
> warranty or not, and the GE call taker can't really advise on this. I
> will see if I can find a GE technician later this afternoon.
>
> Thanks.

My halfpennyworth
Screech- slipping belt
clunks - loose or wonky bearing or bearing support

== 3 of 3 ==
Date: Mon, Mar 14 2011 10:52 am
From: Beloved Leader

On Mar 14, 1:35 pm, "N_Cook" <dive...@tcp.co.uk> wrote:
> Beloved Leader <Kim_Jong...@volcanomail.com> wrote in message
>
> My halfpennyworth
> Screech- slipping belt
> clunks - loose or wonky bearing or bearing support- Hide quoted text -

That the screech was caused by a slipping belt makes sense. I thought
of that too. The belt is barely over two years old, the same age as
the machine. There is good tension in the belt. I could not smell any
burning odor.

If it is the case that a tub shaft bearing is giving out, a seizure in
the bearing could cause the belt to slip against the drive pulley. The
ratio of the sizes of the two pulleys, drive and driven, is just about
that of a Dual belt drive turntable. Scale those up to washing machine
size, and you can imagine how big they are.

In the GE, the motor changes direction twice each agitation. It turns
the drum clockwise, stops, turns the drum counterclockwise, stops, and
then repeats that until the wash or rinse cycle stops. It does not
turn solely in one direction.

Thanks.

==============================================================================
TOPIC: Looking for 6" paper edge speaker
http://groups.google.com/group/sci.electronics.repair/t/0855e1f20eb0f586?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Mar 14 2011 10:59 am
From: boardjunkie1

I need a bunch of 6" or 6.5" cheap-ish quality speakers. They need to
be "extended range" paper edge types, not foam edge low freq drivers.
The application will be in miniature 4-12 style guitar spkr cabinets.
There are spkrs in them now, but they are more of a woofer style with
rolled cloth edge and they don't sound so hot for guitar use.

I've checked all the "usual suspect" surplus houses, and the closest I
came up with was these:
http://www.electronix.com/25-watt-woofer-speaker-ohm-p-13518.html

These *may* work fine, but I'd like more options. Maybe something that
has a 1" coil for a bit better low end response. I can't believe that
vanilla 6" speakers are so hard to find these days. There are guitar
specific 6" drivers made by Weber and Jensen, but for the qty I need I
don't think they are worth the asking price. They're nothing more than
mediocre quality drivers to begin with. Anyone know of anything else
out there that I may have missed before I let an order fly?

==============================================================================
TOPIC: DJ-Tech S-1 ...
http://groups.google.com/group/sci.electronics.repair/t/ee3f29717f1b06b5?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Mar 14 2011 3:11 pm
From: b

On Mar 10, 7:09 pm, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
> "Arfa Daily" <arfa.da...@ntlworld.com> wrote in message
>
> news:506ep.62072$FV5.1779@newsfe28.ams2...
>
>
>
>
>
> > "N_Cook" <dive...@tcp.co.uk> wrote in message
> >news:ilam4o$fv7$1@news.eternal-september.org...
> >> Arfa Daily <arfa.da...@ntlworld.com> wrote in message
> >>news:c%2ep.24512$2H.21966@newsfe15.ams2...
> >>> Anyone got any knowledge / experience of this "Professional Twin SD MP3
> >>> player" ?
>
> >>> This one is from a customer who's lost his user guide. If you go to DJ
> >>> Tech's website, even though the unit is only a few years old, they list
> >>> it
> >>> as 'legacy' and only have a basic spec listed for download - no manuals.
> >>> Needless to say, they don't respond to requests for help in this regard.
>
> >>> The problem with the unit is that when you power it up, ( the soft
> >>> power
> >>> button works ok at this time), the message "UpdateUI--"
> >>> appears
> >> in
> >>> the left window. Anyone know what exactly it's trying to tell us, and
> >>> whether it's correctable with a master reset or something ? I'm guessing
> >>> that the "UI" bit might be User Interface ?? Beyond this initial
> >>> message,
> >> it
> >>> does nothing, and doesn't respond to any controls, including the power
> >>> button. The only way to then get it to power back off, is to remove
> >>> power
> >>> from the wall wart.
>
> >>> Arfa
>
> >> Sometimes archive.org has legacy copies of older websites with the then
> >> current user manuals
>
> > Thanks. I'll give it a look.
>
> > Arfa
>
> Nope. 'Fraid not. They haven't got that page archived.
>
> Arfa

Could it be that there is a noisy power line wreaking havoc with the
uPc? try another psu.

beyond that, it's schematics-and-scope time, or you're buggered...
B

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